But his latest off-the-cuff remark has landed him in some hot water.
Omar Khadr was released on bail on Thursday after spending nearly half of his 28-year life in prison. He is appealing his previous convictions of killing a U.S. soldier with a grenade in Afghanistan.
He was born in Toronto but spent much of his early life in Pakistan, and then Afghanistan. His father moved the family to Osama bin Laden's compound in Jalalabad, in Taliban-controlled eastern Afghanistan, in 1996.
McMillan told CBC News that he regrets sending the tweet through the restaurant Twitter account.
"I felt he was a victim of his father's influence [as] a child. I felt sorry for him whilst watching his press conference. I tweeted a sympathy tweet and anger at Stephen Harper I have from multiple subjects, In retrospect, I should not have done it from the restaurant Twitter account. I did not know all the details and it was based on emotion at that moment. I felt empathy and acted on it. It was a bad call," he said in an email.
Canadian pundit Ezra Levant spotted the tweet and whipped his Twitter followers into a frenzy by calling for a Joe Beef boycott.
McMillan on Friday morning publicly expressed regret for his controversial tweet: